KR101101722B1 - Coordinating transmission scheduling among multiple base stations - Google Patents

Abstract

A method and apparatus for scheduling transmissions of a plurality of cells in a wireless communication system including one or more base stations is provided. The method includes enabling inter-cell transmissions orthogonal to intra-cell transmissions orthogonal to another transmission in each cell of the plurality of cells and other transmissions across a cluster of cells associated with one or more base stations. Providing a set of virtual channels. The method further includes exchanging signaling messages between two or more base stations to coordinate scheduling of inter-cell transmission and intra-cell transmission for the cluster of cells. In order to optimize the parameters associated with the scheduling of the plurality of users from the cluster of cells in the wireless communication system, the optimum power level for each active user's parameter can be retrieved to maximize the indication of the system capacity of the wireless communication system. This enables co-ordinated scheduling of active users in the cluster of cells based on the optimal power levels so that the total interference in the cluster can be minimized to maximize system throughput / capacity.

System throughput, signaling messages, virtual channels, inter-cells, intra-cells

Description

Coordination of transmission scheduling among multiple base stations {COORDINATING TRANSMISSION SCHEDULING AMONG MULTIPLE BASE STATIONS}

The present invention relates generally to telecommunications and, more particularly, to wireless communications.

In multi-user network environments, because many users want to access network resources, scheduling is a useful technique for determining how users can access network resources. In many wireless communication systems, for example, multiple users access a common access medium. Scheduling algorithms typically determine the allocation of channels to provide each user access to a common access medium with minimal interference to other users. Scheduling algorithms in a communication network may, for example, determine the effective use of network resources to maximize network throughput.

Since multiple users seek access to the network, the scheduler can provide access that maximizes network throughput with the Quality of Service (QoS) required for communications. For example, in a wireless communication network, a base station controller (BSC) or radio network controller (RCN) is a reverse link (RL) or uplink (RL) from mobile stations to base stations. UL) may schedule communications. Or, the base station can schedule forward link (FL) or downlink (DL) communications in adjacent cells served by other base stations. A mobile station in handoff communicates with two or more base stations, as this mobile station transitions from one base station to another, and affects the scheduling of communications between them. To schedule data packet transmissions on the reverse link from the mobile station, the base station exhibits a data rate, radio resource and corresponding power level that can reduce interference from these communications.

Wireless communication systems range from first generation analog cellular systems (AMPS) systems to second generation digital cellular systems (CDMA One, TDMA, and Global System for Mobile communications (GSM)), and third generation. Digital multimedia systems (CDMA2000 1X, and Universal Mobile Telecommunications System (UMTS)), high-speed data systems (CDMA2000 Evolution-Data Optimized (EV-DO) and UMTS High-Speed Downlink Packet Access (HSDPA) / Enhanced Dedicated Channel (E) -DCH)).

While third generation wireless systems can support multimedia services with the required QoS, the efficiency of third generation wireless systems for robust data transmission is such that the system is a circuit-switching type system. Because it is not high. On the other hand, a packet switching type of high-speed data system uses scheduling with radio channel awareness in effective radio resource sharing and transmission. Such scheduling coordinates shared access based on feedback of respective radio channel conditions. By scheduling transmissions for good channel users in any short time period, a fast scheduling approach improves system data throughput. In order to respond to changing radio channel conditions to provide relatively high effective data transmission, scheduling and resource management functions are relocated to the base stations. For example, downlink radio resources in both the time domain and the frequency domain can be controlled by the base station's scheduler. The scheduling algorithm may assign one or more channels or sub-channels to the mobile station. Resource allocation typically includes determining powers and / or bandwidth to optimize performance in a cell served by a base station.

Many high-speed packet switching systems, including HSDPA and E-DCH, provide the time, power, data rate, overall system rise over thermal (RoT), and the physical layer of users in the same cell. It focuses on optimizing shared access control for forms. Optimization of shared access control relates to control of the interference source. When shared access control is applied only within one cell, cross interference for another cell (inter-cell interference is generated in proportion to the signal strength for the intra-cell) This interference limits the ability to improve the overall system signal-to-noise ratio (SNR) and spectral efficiency, which is based on the encoding method that codes the information. Is to measure the performance of the encoding to transmit bits at a given data rate.

In general, interference management can be classified into three categories: interference avoidance, interference coordination, and interference mitigation. Interference avoidance involves creating a strategy and executing the strategy independently in each cell for shared access control to reduce interference with each other. Interference coordination coordinates strategies between cells to further suppress potential interference. Interference mitigation reduces the potential interference between cells served by a base station and neighboring cells by transmitting in parallel between cells.

More specifically, interference avoidance or coordination schemes suppress mutual interference by creating an orthogonal set at time (time sharing) or frequency (frequency reuse). Management of synchronized and transmitted power between nodes, such as base stations, can reduce mutual interference. Interference avoidance or coordination schemes control the interference level to satisfy the required QoS levels of each service. However, time / frequency sharing or transmitted power management strategies do not improve spectral efficiency.

Interference mitigation schemes may also be implemented to reduce interference between the cell serviced by the base station and adjacent cells. For example, base stations in adjacent cells may transmit using the same set of frequency channels. If both base stations assign the same frequency channel to different mobile units, the mobile units can receive a composite signal that includes signals from both base stations on the assigned frequency channel. A portion of the composite signal is the desired signal and another portion of the composite signal will be considered interference, which is commonly referred to as "inter-cell interference". Inter-cell interference interferes with and potentially disrupts communication with mobile units. Therefore, interference mitigation schemes typically minimize inter-cell interference by adjusting the allocation of radio channels between base stations serving adjacent cells, and the power allocated to each channel.

In wireless communications, some interference is also caused by the lack of coordination between transmissions and resource management. Many cellular communication systems manage interferences and noise through cell planning, interference coordination, interference avoidance, transmitted power control, transmitted rate adaptation, or radio resource management schemes. Some interference management schemes adjust radio resources based on the level of received interference and the allowable interference to meet QoS requirements. Fast communication links between nodes and large scale radio resource management in real time can control transmission based on relatively fast radio channel feedback over an air interface, and coordinate transmission between cells for interference management. Can be. To improve system performance, a high speed radio access system adapts communication links between nodes or base stations. However, signal-to-interference ratio (SIR) limits link adaptation because interference limits the SIR caused by neighboring systems. To provide interference management, high speed data systems such as UMTS HSDPA / E-DCH systems incorporate relatively fast feedback and transmission rate adaptation of radio channel conditions. However, this passive interference management provides limited gains in system performance and spectral efficiency. In addition, passive bandwidth CDMA (W-CDMA) and HSDPA systems in interference management may not provide the desired system performance and spectral efficiency.

Some access technologies use aggressive interference management schemes. Two examples of aggressive interference management schemes include CDMA interference cancellation (or UL multi-user detection) and pre-coding techniques. The interference cancellation scheme predicts interference at the receivers and subtracts re-encode interference from the received signals for further demodulation. However, interference cancellation techniques are limited by the predicted accuracy of the interference at the receiver, which is determined by the received signal to noise ratio. Pre-coding techniques incorporate predicted interference into the channel coding of the transmitted signal to minimize interference at the receiver side. However, the necessary knowledge of the channel response in real time for channel coding limits the pre-coding technique. Thus, interference cancellation and pre-coding techniques have serious consequences for performance degradation if the expected interference is inaccurate because the predicted errors in the cancellation of the planned interference introduce other sources of interference.

In the following, a simplified summary of the invention is provided to provide a basic understanding of some aspects of the invention. This summary is not an exhaustive overview of the invention. It is not intended to identify key or critical elements of the invention and to delineate the scope of the invention. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

The present invention addresses or at least reduces one or more of the problems and the effects described above.

In one embodiment of the present invention, a method of scheduling transmissions of multiple cells in a wireless communication system including one or more base stations is provided. The method provides a set of channels to enable orthogonal inter-cell transmissions within each cell of a plurality of cells, and intra-cell transmissions that are orthogonal across a cluster of cells associated with one or more base stations. It includes. The method further includes coordinating the scheduling of intra-cell transmissions with inter-cell transmissions for a cluster of cells between at least two base stations of the one or more base stations.

In yet another embodiment, a method is provided for optimizing a parameter associated with scheduling of a plurality of users from a cluster of cells in a wireless communication system. The method includes searching for an optimal power level for each user parameter of the plurality of users to maximize the indication of the system capacity of the wireless communication system. The method further includes scheduling the plurality of users active in the cluster of cells based on the optimal power levels.

The invention may be understood by reference to the following description taken in conjunction with the accompanying drawings, wherein like reference numerals identify like elements.

1 is a long term evolution comprising a joint virtual scheduler and first and second base stations for scheduling transmissions of a plurality of cells in a relatively high speed radio access network according to an exemplary embodiment of the present invention. Long Term Evolution (LTE) A schematic diagram of a wireless communication system such as a UMTS system.

FIG. 2 is a schematic illustration of an architecture of joint scheduling for an LTE UMTS system in which the joint virtual scheduler shown in FIG. 1 may find an application, in accordance with an exemplary embodiment of the present invention. FIG.

FIG. 3 implements a method that may utilize a set of virtual channels of active users and together with intra-cell transmissions for a cluster of cells in the wireless communication system shown in FIG. 1 in accordance with an exemplary embodiment of the present invention. A stylized representation of signaling messages between base stations to coordinate joint scheduling of inter-cell transmissions.

4 is a frequency for transmissions from base stations to active access terminals in a cluster of cells to maximize the total throughput or capacity for each base station shown in FIG. 1, according to one embodiment of the invention. A stylized representation implementing a method of scheduling power in a domain.

5 is in the time domain for transmissions from base stations to active access terminals in a cluster of cells to maximize the total throughput or capacity for each base station shown in FIG. 1, according to one exemplary embodiment of the present invention. A stylized representation implementing a method of scheduling power.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are described in detail herein. However, the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, and on the contrary, the invention is to be accorded the scope and spirit of the invention as defined by the appended claims. It is to be understood that the changes, equivalents and alternatives are included.

Exemplary embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. In the development of any such practical embodiment, decisions specific to various implementations may be made to achieve specific goals of developers that may vary from one implementation to another, such as by system and business constraints. It will of course be understood that numerous implementation-specific decisions can be made. It will also be appreciated that such development efforts are complex and time-consuming, but will nevertheless be routine undertakings to those skilled in the art having the benefit of this disclosure.

In general, a method and apparatus are provided for coordinating transmission scheduling among a plurality of access nodes or base stations. By utilizing resource management in real time and relatively fast communication between access nodes or base stations, Universal Mobile Telephone System (UMTS) LTE controls transmission and suppresses interference based on fast radio channel feedback over the air interface. The transmission between cells for management can be coordinated. In particular, the joint scheduler can manage one or more radio resources of all base stations in a cluster in real time and can cooperatively control interference to optimize overall system performance. By using radio resource management and interference mitigation, the joint scheduler can maximize the signal-to-noise ratio of the received signal, thus improving system spectral efficiency. The joint scheduler can coordinate the transmissions of cells in the cluster to minimize the overall interference. By coordinating the communications of the cells together in a cluster, the joint scheduler can reduce interference from other neighboring cells and can instead provide signal strength enhancement. Interference management can minimize the generation of interference, and the power transmitted can be transformed into gains, which can increase spectral efficiency and enhance system capacity for each cell with universal reuse. As a result, the joint scheduler can create a super set of virtual channels orthogonal across all cells in the cluster. Interference mitigation can enhance the signal-to-noise ratio of the received signal. The super virtual channel set includes a set of virtual channels that can be used in each cell with universal reuse. Since virtual channels in a super virtual channel set are orthogonal to each other within and across cells, a super virtual channel set for all cells in a cluster can cause transmissions to be orthogonal to one another (intra and inter) cells. This orthogonal inter-cell and intra-cell transmission can minimize the total interference within the cluster. The joint scheduler can support multiple access schemes and the following physical layer forms. Optimization of system performance for different multiple access schemes and the physical layer types below may be based on information available for optimization. The joint scheduler cannot rely on feedback or ideal knowledge of radio channel conditions.

1 illustrates a joint virtual scheduler for scheduling transmissions of a plurality of geographic regions or cells 110 (1-m) in a relatively fast radio access network 115 in accordance with one exemplary embodiment of the present invention. 108 is a schematic illustration of a wireless communication system such as UMTS LTE including 108 and first and second base stations 105 (1, 2). Each base station of the first and second base stations 105 (1, 2) may serve one or more cells 110 (1-m). By using one or more base stations 105 (1, 2), a number of access terminals 120 (1, 2) and 125 (1) active within cells 110 (1-m). (ATs, also known as User Equipment (UE), mobile stations, etc.) may be used for high speed radio access networks 115 and other interconnected electrical systems such as publicly switched telephone systems (PSTNs) and data networks. Access to communication systems. In order to provide wireless connectivity to access terminals 120 (1, 2) and 125 (1), base stations 105 (1, 2) are eventually cells 110 (1-m). May be communicated with a server 122 that connects to the UMTS LTE system 100.

For illustration, the wireless communication system of FIG. 1 is a UMTS LTE system 100, but it should be understood that the present invention may be applicable to other systems that support data and / or voice communication. The UMTS LTE system 100 has some similarities to the conventional UMTS system, but is substantially different with respect to the operation of the instant invention for the first and second base stations 105 (1, 2). In the system 100, the joint virtual scheduler 108 may be functionally deployed at the server or alternatively deployed at the server to coordinate the transmissions for the cluster 110a of cells in a relatively centralized manner. It may be distributed to the base stations 105 (1, 2) .However, instead of scheduling transmissions of a single cell or neighbor cells, the joint virtual scheduler 108 may be configured to allow a large number of active users to access the high speed radio access network 115. Transmissions for the cluster 110a of cells that can find access to the shared resource of < RTI ID = 0.0 >

Thus, it should be appreciated that a coordinated joint virtual scheduling scheme for the UMTS LTE system 100 may be useful for at least two examples. The first is to reduce intra-cell interference within cell 110 of cluster of cells 110a in solidarity with inter-cell interference caused by transmissions of neighboring or nearby cells in cluster of cells 110a. For the second, during hand-offs of the ATs 120 from one base station of the first and second base stations 105 (1, 2) to another base station. The coordinated joint virtual scheduling scheme may support diversity combining and / or soft-handover for active users of the cluster of cells 110a in the fast packet access interface. The coordinated joint virtual scheduling scheme may generate one or more inter-cell interference sources for each user to provide signal enhancement in the handover region. For example, the coordinated joint virtual scheduling scheme may be a fast packet access interface for a set of channels, such as virtual channels 145, from each cell of the cluster 110a of cells associated with diversity combining and / or soft-handover. It is possible to provide a macro diversity gain in each signal received on the physical channel of.

The UMTS LTE system 100 and the server 122 can operate according to Universal Mobile Telecommunication Services (UMTS) protocols and can implement Orthogonal Frequency Division Multiple Access (OFDMA). have. However, those skilled in the art having the benefit of the present invention should understand that the present invention is not limited to communication systems operating in accordance with UMTS and / or OFDMA. In alternative embodiments, UMTS LTE system 100 includes but is not limited to a Global System for Mobile communication (GSM), Code Division Multiple Access (CDMA, CDMA2000), and the like. May operate according to one or more other protocols.

Specifically, each base station of the first and second base stations 105 (1, 2) has a code division multiple access (CDMA, cdma2000) protocol, an Evoloved Data Optimized (EVDO, 1XEVDO) protocol, a UMTS protocol. Provide wireless connectivity to access terminals 120 (1, 2) and 125 (1) according to any desired protocol, including, GSM protocol, and the like. The cdma2000 1xEV-DO specification uses the terms "access network" for the base station and "access terminal" for the mobile station, but in the illustrated embodiment, the access network 115 It is shown separately from the base stations 105 (1, 2).

Examples of access terminals 120 (1, 2) and 125 (1) are cellular telephones, personal digital assistants using a spread spectrum communication system to operate in a high speed wireless data network 120, such as a digital cellular CDMA network. personal digital assistants (PDAs), and a host of wireless communication devices including, but not limited to, GPSs Other Examples of Access Terminals 120 (1, 2) and 125 (1) These may include smart phones, text messaging devices, and the like.

In the UMTS LTE system 100, the fast radio access network 115 may use any desired protocol, such that the first and second base stations 105 (1, 2) and access terminals in accordance with any desired protocol. Wireless communication between 120 (1, 2) and 125 (1). Examples of such protocols include (CDMA, cdma2000) protocols, Advanced Data Optimization (EVDO, 1XEVDO) protocols, UMTS protocols, GSM protocols, and the like.

Other examples of such protocols include the 1xEV-DO protocol, UMTS protocol, GSM protocol, and the like. 3G cellular systems based on any one of these protocols, etc. provide improved voice capacity and support high data rate packet based services. As one example, these features are provided in the cdma2000 1xEV high rate packet air interface referred to as IS-856. More specifically, the 3G cellular system cdma2000 1xEV provides users with high speed wireless Internet access with asymmetric data traffic for cellular networks based on the IS-95 standard. For example, the data rate of active users in access terminal 120 (1) may vary from 9.6 kbps to 153.6 kbps.

Base stations 105 (1, 2) may allocate a plurality of channels within the frequency spectrum across communicating with access terminals 120 (1, 2) and 125 (1). An access terminal 120 (1) within range of both the first and second base stations 105 (1, 2) may communicate with the base station using these channels. In this way, the base stations 105 (1, 2) may provide wireless connectivity to corresponding geographic regions or cells 110 (1-m). As discussed above, base stations 105 (1, 2) may provide wireless connectivity and implement OFDMA in accordance with UMTS protocols, but base stations 110 are not limited to these protocols. In the illustrated embodiment, the first base station 105 (1) provides wireless connectivity to the access terminals 120 (1, 2) and the second base station 105 (2) provides access terminals 125 ( 1) provide wireless connectivity. However, those skilled in the art having the benefit of the present invention will appreciate that base stations may provide wireless connectivity to any number of access terminals at any location in or near cells 110 (1-m). Can be.

The first base station 105 (1) may provide one or more intra-cell transmissions (TXs) 130 (1, 2) to the access terminals 120 (1, 2), respectively, while 2 Base station 105 (2) may provide one or more intra-cell transmissions 135 (1) to access terminal 125 (1), and one or more inter-cells to access terminal 120 (1). May provide cell transmissions (TXs) 135 (2). In the illustrated embodiment, the inter-cell and intra-cell transmissions 130, 135 comprise one or more channels within the selected frequency band, for example, the sub-carriers are in accordance with the OFDMA scheme. Can be prescribed. Those skilled in the art should appreciate that sub-carriers may also be referred to using terms such as frequency channels, sub-channels, tones, and the like.

To schedule the transmissions for the cluster 110a of cells in parallel, the joint virtual scheduler 108 may include a parameter optimization algorithm 140 that determines power allocations for active users in the cluster of cells 110a. . Based on the given maximum power limit of each base station 105, the parameter optimization algorithm 140 maximizes the total throughput / capacity of the UMTS LTE system 100 and co-channel interference. The transmission power from the base stations 105 to the access terminal 120 or 125 on a particular channel or sub-channel is determined such that this is minimized.

In CELL_1 110 (1), base station 105 (1) is intra-transmitted to send information to access terminals 120 (1, 2) at the corresponding power allocation indicated by parameter optimization algorithm 140. Different channels may be used for cell transmissions (TXs) 130 (1, 2). However, intra-cell transmission 135 (1) to access terminal 125 (1) and inter-station from base station 105 (1) to access terminal 120 (1) in cell CELL_2 110 (2). Cell transmission 135 (2) may be scheduled in conjunction with CELL_1 110 (1). That is, the base station 105 (1) in the cell CELL_2 110 (2) of the cluster of cells 110a allows the base station 105 (1) to receive intra-cell transmissions 130 (without increasing inter-cell interference). 1,2)) may use the same channel for inter-cell transmission 135 (2) to access terminal 120 (1). In order to optimize the overall performance parameters, for example the system throughput / capacity of the UMTS LTE system 100, the parameter optimization algorithm 140 clusters the clusters by chronologically minimizing the parameters that produce interference between the clusters of cells 110a. Interference between the cells of 110a can be controlled.

By managing one or more radio resources, such as the transmit power of the base stations 105 (1, 2) in real time, the joint virtual scheduler 108 is coupled with the inter-cell transmission 135 (2) of the cluster 110a of cells. Intra-cell transmissions 130 (1, 2) and 135 (1) may be scheduled together. As an example, the parameter optimization algorithm 140 may convert the indication of transmitted power into a diversity gain. Thus, the power of inter-cell and intra-cell transmissions 130, 135 on the channels can be scheduled in a manner that mitigates inter-cell and / or intra-cell interferences.

In cellular communications, in addition to the radio channel or frequency used for signal transmission, a virtual channel is used to integrate multiple disparate channels, for example to collect feedback for analysis at signal location. . In the first generation, the virtual channel is a narrow band frequency carrier (FDMA) with a frequency reuse pattern between cells. Second generation GSM systems have a virtual channel in a time slot (TDMA) with a frequency reuse pattern between cells. FDMA and TDMA type virtual channels rely on the operation of frequency / time separation. The frequency reuse pattern controls common channel interference from the same frequency at time during cell planning. Interference management in frequency reuse planning considers the worst-case scenario static at the cell edge as a target.

A third generation wideband CDMA (W-CDMA) system is a spreading code (or channelization code) as a virtual channel with universal frequency reuse by masking with a different scrambling code for each cell. code)). Downlink (DL) W-CDMA channels are orthogonal to each other in the code space within cell 110, while uplink (UL) W-CDMA channels receive simultaneous user mobility among all users. are not orthogonal to each other because they prevent synchronous receptions. In a W-CDMA system, control of the transmitted power provides interference management because the power control function manages both intra-cell and inter-cell interference. However, this power control does not affect the interference.

In a DL HSDPA system, virtual channels are divided in both code space and time space. In HSDPA systems, virtual channels are assigned by the scheduler to maximize data throughput in the Transmission Time Interval (TTI) by quickly responding to radio channel measurement feedback. With the use of shorter TTI intervals, such as 2ms, the HSDPA system allows for higher speed transmission at the physical layer. Because virtual channels are orthogonal to each other within cell 110 in an HSDPA system, interference management minimizes inter-cell interference based on the power allocation transmitted.

In operation, the joint virtual scheduler 108 is orthogonal intra-cell transmissions 130 (1, 2 and 135 (1)) within each cell 110 of the plurality of cells 110 (1-m) and Provide a set of virtual channels 145 to enable orthogonal inter-cell transmission 135 (2) across the cluster 110 a of cells associated with the base stations 105 (1, 2) have. The parameter optimization algorithm 140 may divide the set of virtual channels 145 by time, frequency, space, antenna, and / or codes for the cells of the cluster 110a. For example, dynamic partitioning of a resource in a set of virtual channels 145 in real time may adapt to an indication of user mobility and channel variation of each user within a cluster of cells 110a. Can be.

In order to coordinate the scheduling of intra-cell transmissions 130 (1, 2) and 135 (1) with inter-cell transmission 135 (2) for cluster 110a of cells, the base stations 105 ( 1, 2) may exchange signaling messages (SIG_MSG) 150 (1, 2) between them. As described below, the joint virtual scheduler 108 is inter-cell transmission 135 (2) along with intra-cell transmissions 130 (1, 2) and 135 (1) for cluster 110a of cells. Signaling messages 150 (1, 2) between base stations 105 (1, 2) may be used to coordinate scheduling of the < RTI ID = 0.0 >

According to one embodiment, the joint virtual scheduler 108 schedules a virtual channel of the set of virtual channels 145 for each user and interconnects the base stations 105 (1, 2) with a virtual interconnect. It may be distributed to the base stations 105 (1, 2). The virtual interconnect may include first and second scheduling channels (SC_CH) 155 (1, 2) and first and second feedback channels (FB_CH) 160 (1, 2). The joint virtual scheduler 108 may communicate power allocations for active users via the first scheduling channel (SC_CH) 155 (1) to the first base station 105 (1), and the first feedback channel (FB_CH). The feedback may be received through the 160 (1). Similarly, the second base stations 105 (2) may receive power allocations for active users via a second scheduling channel (SC_CH) 155 (2), and a second feedback channel (FB_CH) 160. (2)) may receive the feedback.

By using the high speed communication link 170 (1) between the base stations 105 (1, 2), the joint virtual scheduler 108 may collect feedback information and user information from each base station. Based on the feedback information and the user information, the joint virtual scheduler 108 may assign each user in the cluster of cells 110a a virtual channel of the set of virtual channels 145. In particular, the joint virtual scheduler 108 may fetch user information about radio resource characteristics for each user and cross-correlate between the cells of the cluster 110a to manage overall interference to the cluster 110a of cells. the representation of the correlation can be determined.

The joint virtual scheduler 108 transmits the indication and control information of the interference for each base station of the base stations 105 (1, 2) in a time stamp based on the indication of the user information and the cross correlation, Virtual channel allocation and control between cells of the cluster 110a may be coordinated. The joint virtual scheduler 108 may manage global interference on the cells of the cluster 110a and use a common reference time between the cells of the cluster 110a for reference of control information. In order to use a common reference time between the cells of the cluster 110a, the joint virtual scheduler 108 is based on a system and / or frame counter based on the virtual interconnection between the base stations 105 (1, 2). High speed communication link 170 (1) may be synchronized.

According to an alternative embodiment, joint scheduling control based on a client-server architecture assigns each user in a cluster of cells 110a the corresponding virtual channel of the set of virtual channels 145 in tandem. can do. In this exemplary embodiment, in order to control the scheduling of radio resources in a UMTS LTE system 100 and to manage the overall interference to the cluster 110a of cells, the joint virtual scheduler 108 is configured to each base station 105. Can be treated as a client to a dedicated scheduling server. The dedicated scheduling server may collect feedback and user information from the cluster 110a of cells as input to the joint virtual scheduler 108.

However, in an OFDMA interface, a coordinated joint virtual scheduling scheme is used to reduce the common channel interference of one or more sources from the neighboring cell 110 (m) of the cluster of cells 110a to diversity transmission. It can support macro-diversity coherent combining. The coordinated joint virtual scheduling scheme may substantially schedule the same set of data transmissions of each sub-channel from each cell of the cells of the cluster 110a for the user and / or adjust the age allocation of these sub-channels.

FIG. 2 schematically illustrates the architecture 200 of solidarity scheduling for a UMTS LTE system 100 in which the joint virtual scheduler 108 shown in FIG. 1 may find an application in accordance with one exemplary embodiment of the present invention. Drawing. By using the architecture of solidarity scheduling 200, the UMTS LTE system 100 can control intra-cell transmissions 130 (1, 2) and 135 (1) based on air channel feedback over the air interface. In addition, inter-cell transmission 135 (2) may be coordinated between cells of cluster 110a to provide interference management. The joint virtual scheduler 108 controls all base stations 115 (1, 1) within the cluster 110a of cells in real time to cooperatively control intra-cell and inter-cell interference to optimize overall system performance by such interference mitigation. 2) can manage radio resources. This combined radio resource management and interference mitigation can maximize the signal-to-noise ratio (SNR) of the received signal, thus improving system spectral efficiency.

The architecture of solidarity scheduling 200 may support a plurality of multiple-access schemes 205 to provide each user access to a common access medium, without interfering with other users. Examples of multiple multiple-access schemes 205 include Orthogonal Frequency Division Multiple Access (OFDMA) 205 (1), Code Division Multiple Access (CDMA) sub-channel ( 205 (2)), time division multiple access (TDMA), frequency division multiple access (FDMA), and the like. Methods for multiple access are known in the art, and in terms of clarity, only those aspects of the multiple-access schemes 205 related to the present invention will be further described herein.

The architecture of solidarity scheduling 200 includes multiple-input multi-output (MIMO) 210 (1), pre-coding 210 (2), and network coding 210 (3). Can support a plurality of physical layer forms 210, such as beam-forming 210 (4), transmitted diversity, space-time coding, and the like. have. Techniques for physical layer forms are known in the art, and in terms of clarity, only those aspects of physical layer forms 210 associated with the present invention will be described herein.

For the different multiple access schemes of the plurality of physical layer forms 210 and the plurality of multiple-access schemes 205, the optimization of the system performance metric is based on feedback or knowledge of the radio channel state. It may be based on the degree of information available for the same optimization. In particular, the joint virtual scheduler 108 measures the signal quality of the received (RX) signal 215 (1) of distributed joint virtual scheduling, the channel (CH) characteristic 215 (2) and the channel predicate. Feedback 215 may be used, including but not limited to 215 (3). In order to provide inter-cell and intra-cell transmission (TX) control 220, architecture of regiment scheduling 200 includes TX schedule 220 (1), TX power 220 (2), and TX bandwidth ( 220 (3)).

In dividing the set of virtual channels 145 into time, frequency, space, antenna, and / or codes for the cluster of cells 110a, the combination of these variables for the virtual channel is the physical layer type 210. And the use of a multiple-access scheme 205. Resource partitioning for virtual channels must be dynamic in real time to adapt to user mobility and channel changes of each user.

According to one embodiment of the joint virtual scheduler 108, the joint virtual scheduler 108 may support soft-handover for the HSDPA system. In HSDPA systems, one of the main interference sources is inter-cell interference. For example, significant inter-cell interference is observed in areas where associated dedicated channels (DCHs) are in soft-handover. If soft-handover is supported for HSDPA users, the sources of inter-cell interference for each user cause signal enhancement when the users are in the handover area. When soft-handover is supported for HSDPA users, the virtual channel includes HSPDA physical channels from all cells 110 involved in the handover and has macro diversity gain in the received signals. As the joint virtual scheduler 108 controls the interference, the joint virtual scheduler 108 may support HSDPA soft-handover for HSDPA users, as inter-cell interference is mitigated and eventually provides signal enhancement.

Another embodiment of the joint virtual scheduler 108 may support macro-diversity coherent combining at the OFDMA air interface. In an OFDMA system, one of the main interference sources is co-channel from neighboring cell 110 (m), as shown in FIG. In the case of general purpose reuse, in an OFDMA system, when the contents of each sub-channel are different from other cells 110 and scheduled independently for transmission, mutual interferences are covered by multiple cells 110. Is created in the overlapping region. The macro-diversity scheme can schedule the same set of data transmissions of sub-channels from all cells in the overlap region for a particular user. Since the virtual channel of an OFDMA system with a macro-diversity scheme provides an orthogonal set in the overlap region, interference can be mitigated as signal enhancement. For age scheduling in an OFDMA system, the joint virtual scheduler 108 may adjust the sub-channel age assignments for all cells in the cluster 110a.

3 illustrates transmissions 130 (1,2), 135 (1), based on power allocations in the UMTS LTE system 100 shown in FIG. 1, in accordance with an exemplary embodiment of the present invention. And a stylized representation to implement a method of coordinating date scheduling of 135 (2). At block 300, the joint virtual scheduler 108 includes inter-cell transmissions 135 (2) along with intra-cell transmissions 130 (1, 2) and 135 (1) for the cluster of cells 110a. ) Can use the set of virtual channels 145 for active users and the signaling messages (SIG_MSG) 150 (1, 2) between the base stations 105 (1, 2). Inter-cell transmission 135 (2) orthogonal across cluster 110a of cells associated with base stations 105 (1, 2) and a cluster of cells of plurality of cells 110 (1-m) ( In order to enable intra-cell transmissions 130 (1, 2) and 135 (1) orthogonal within 110a), the joint virtual scheduler 108 is virtual to each user in the cluster of cells 110a. A set of virtual channels 145 can be provided to assign a channel.

At block 305, by exchanging signaling messages (SIG_MSG) 150 (1, 2) between the base stations 105 (1, 2), the joint virtual scheduler 108 is assigned to the cluster of cells 110a. The scheduling of inter-cell transmissions 135 (2) may be coordinated with intra-cell transmissions 130 (1, 2) and 135 (1). The joint virtual scheduler 108 may coordinate virtual channel allocation and control between the cells of the cluster 110a to manage overall interference to the cluster of cells 110a. Using the parameter optimization algorithm 140, the joint virtual scheduler 108 determines power allocations of optimal power levels for active users and communicates to the first and second base stations 105 (1, 2), respectively. Can be. Based on the optimal power levels that maximize the system throughput / capacity of the UMTS LTE system 100, the joint virtual scheduler 108 may access active users within the cluster 110a of cells, as indicated at block 310. The terminals 120 (1, 2) and 125 (1) may be scheduled in solidarity.

According to one embodiment of the invention, the joint virtual scheduler 108 may be an aggressive interference coordination scheme that coordinates control and allocation between cells of the cluster 110a. Joint virtual scheduler 108 provides a high speed data link 170 (1) for optimal performance between processing nodes, i.e., cells, or associated processors of base stations 105 providing relatively fast communication between cells 110. FIG. In dependence, the UMTS LTE system 100 may enable cross-correlation between cells 110 for interference management and information of radio channel characteristics for each user. To provide interference management, the joint virtual scheduler 108 may communicate control information, such as an accurate time stamp, to each base station 105. This information exchange may take place over a high speed data link 170 (1) between processing nodes, which may include base stations 105, controllers, and / or processors.

However, the conventional UMTS system specification specifies a 5 ms U-plane UMTE Terrestrial Radio Access Network (UMTRAN) delay requirement in the unloaded state. . This U-plane delay is the one-way transmission time between packets available in the Internet Protocol (IP) at user equipment (UE), such as the AT 120 / Radio Access Network (RAN) edge node. It is defined for the availability of this packet in the IP layer of the RAN edge node / UE, ie AT 120. This RAN edge node is a node that provides a RAN interface towards the core network (CN).

The specifications of the UMTS LTE system 100 may enable advanced UTRAN (E-UTRAN) U plane latency of less than 5 ms in an unloaded state (ie, a single user with a single data flow) for small IP packets. For example, 0 byte payload + IP headers in the E-UTRAN bandwidth mode may affect the experienced latency. This U-plane latency may indicate a need for high speed interconnection between processing nodes, such as base stations 105 in the UTRAN. However, in conventional UMTS systems, IP transmission over T1 / E1 / J1 in UTRAN may not meet the UTRAN latency threshold. To meet the delay threshold, 10 BaseT Ethernet, 100 BaseT Ethernet, Gigabit Ethernet, 10 Gigabit Ethernet or 100 Gigabit Ethernet may provide interconnection between processing nodes including base stations 105. For example, high capacity Gigabit Ethernet supporting such interconnect uses Gigabit Ethernet switches or hops that can support QoS characteristics to control latency in UMTS LTE system 100. By using Gigabit Ethernet as the UTRAN transmission, UMTS LTE system 100 exchanges control and interference management information between processing nodes including base stations 105 having relatively high QoS priorities to minimize latency. You can configure a gigabit Ethernet switch.

The required U-plane delay latency also indicates the use of high speed data processing capability for the data chain in the UTRAN. High speed data links 170 (1) between processing nodes including base stations 105 enable distributed processing capabilities for joint virtual scheduler 108. For example, high speed computation processors may be used in one embodiment to enable distributed processing capabilities. This distributed processing is advantageous for collecting information and calculations for interference management in the joint virtual scheduler 108, as well as reducing the overall cost.

In one exemplary embodiment, in order to coordinate radio resources in UMTS LTE system 100 and manage overall system interference for all cells in cluster 110a, joint virtual scheduler 108 is responsible for all cells in cluster 110a. A common reference time between them can be used. This common reference time between all the cells in the cluster 110a can provide a reference of all control information and interference management, and conventional UMTS systems can achieve the desired high accuracy at the base stations 105 without synchronization between them. Use a free running clock. Although common network clocks for hierarchical and core networks are available in UTRAN, such network clocks may not meet the desired accuracy. Accordingly, in the UMTS LTE system 100, a System Frame Number (SFN), a Node B frame Number (BFN), to provide data link and virtual synchronization between the base stations 105, Frame counters and system counters may be used, such as RNC common frame number (RFN), and cell system frame number (CFN).

Alternatively, in a W-CDMA system where interference is managed through non-coordinated power control, the use of a free running clock with incorrect network synchronization may manipulate inter-interference. Using reference time for other multiple access techniques, such as OFDMA and TDMA with tight synchronization between processing nodes including base stations 105, enables interference management such as interference avoidance and coordination.

In another embodiment, GPS time may be used to provide a common reference time since each cell in cluster 110a may independently measure with substantially the same accuracy. For example, GPS time is used by the CDMA system to synchronize base stations 105 and support handover. Similarly, GPS absolute time may provide a common reference time for joint virtual scheduler 108 to control system information, manage interference, and schedule virtual channels for each cell 110. .

In one embodiment, the architecture 200 shown in FIG. 2 combines the high speed communication links 170 and the base stations 105 (1, 2) in the cluster 110a and all the base stations in a distributed manner. Using a joint virtual scheduler 108 to interconnect 105, it may match a base station router (BSR). A distributed architecture with a virtual controller based on BSR is used to collect user and feedback information from each base station 105 and to allocate virtual channels to all users in the cluster 110a to maximize system performance. It may include a virtual scheduler server, which may be a compute node. The virtual scheduler server may be distributed to each base station 105 such that the base station provides primary nodes for information distribution, parallel computation and information collection for final scheduling and virtual channel assignment. The distributed virtual scheduler server architecture may enhance some of the HSDPA / E-DCH features for high speed communication links 170 between base stations 105 for coordination and management.

Another alternative distributed virtual scheduler server architecture is a dedicated scheduling server for enabling alliance scheduling control in which all base stations 105 act as clients to a dedicated scheduling server. A client-server architecture based on a dedicated scheduler server can be effective in controlling costs, while enabling efficient cooperative virtual channel allocation and overall resource management.

The feedback and user information used by the joint virtual scheduler 108 may include each user's wireless channel conditions, buffer data for each user and its time stamp, user mobility, and user capacity information. In order to minimize interference while maximizing system throughput / capacity, the joint virtual scheduler 108 collects feedback and user information from all cells 110 in the cluster 110a as input, and then based on the feedback and user information. Virtual channel allocation may be performed for each user in the cluster 110a.

In order to optimize the parameters associated with the scheduling of the plurality of users from the cluster of cells 110a, in the UMTS LTE system 100, the joint virtual scheduler 108 sets the optimal power level for the parameters of each user of the plurality of users. You can search. The search algorithm can maximize the indication of the system capacity of the UMTS LTE system 100 by scheduling the plurality of users active in the cluster 110a of cells based on the optimal power levels. For example, the joint virtual scheduler 108 may use a parametric optimization algorithm 140 to retrieve a sub-optimal solution of the resource for each user in the cluster 110a of cells. In this manner, the joint virtual scheduler 108 is an objective function that is the sum of Shannon capacity of a plurality of users in the cluster 110a of cells 110a based on the optimization of the power level. Each user can be scheduled at.

Joint virtual scheduler 108, a matrix A is comprising a matrix of a correlation between the physical layer type shown in Figure 2 for the N people users in a cluster (110a) (210), base stations 105 related, UMTS It may be based on a virtual channel structure model for N users in the LTE system 100 (in entire clusters). Each correlation matrix represents an age channel correlation in space, time, frequency, code, antenna technique, and coding technique. The vector x represents the requested virtual channels for all N users in the joint virtual scheduler 108. The vector x may be a function of space, time, frequency, code, antenna technique, and coding technique in the equation below.

g: general function

s: set of space attenuation functions between users and base stations 105 (1, 2) in cluster 110a. S is a multidimensional attenuation function for all base stations 105 (1, 2) in cluster 110a.

t: set of transmission time slots for transmission between base stations in cluster 110a

f: set of frequency subchannels or frequency bands for a subcarrier.

a: set of antenna patterns and techniques, such as MIMO 210 (1), transmit diversity, beam-forming 210 (4),

c: set of coding and pre-coding schemes

sf: set of time domain spreading codes for spread spectrum communication.

According to one solution of virtual channel assignment, vector x is the eigenvector of correlation matrix A. In this solution, the eigen value of the matrix A represents the energy distribution on each eigenvector. However, matrix A is a function of a number of variables, such as attenuation for each base station, channel correlation between antennas within each base station, frequency selection effects of sub-channels, channel correlation between spreading sequences and time slots. Each variable increases the matrix A dimension multiple times depending on that variable. Multiple variables cause multiple effects on a single variable. The dimensions and complexity of matrix A are greatly increased when all supported physical layer forms 210 and multi-access schemes 205 are considered for all base stations 105 in clusters 110a.

Therefore, in order to obtain the desired solution, the complexity (complicity) of the matrix A is simplified or the general multi-specific correlation matrix A as the physical layer form (210) can be reduced by defining the access method 205. For example, in a typical R-99 single antenna W-CDMA DL system, since time, frequency, code, and antenna are constants, the spreading codes are orthogonal sets within the same scrambling code. In addition, matrix A is a function of cross correlation and space between scrambling codes between base stations 105. Thus, the joint virtual scheduler 108 provides a scrambling set for all base stations 105 to minimize cross-interference for all users in the clusters 110a.

However, if a single antenna HSDPA system is represented for matrix A , joint virtual scheduler 108 includes a time variable to provide a set of scrambling codes that minimizes cross-interference for the user scheduled at that time. Since the HSDPA system supports many multi-user scheduling in the TTI, instead of using a new scrambling code set to minimize inter-interference to obtain a workaround, the joint virtual scheduler 108 may alternatively use the current scramble code set. Interference can be managed. This solution of interference management in an HSDPA system can support soft-handover for all users in the handover area. When the users are in the handover area, the joint virtual scheduler 108 may adjust the transmission time with the same set of HS-PDSCH codes between all base stations 105 participating in soft handover. The joint virtual scheduler 108 can minimize cross or inter-cell interference because the interference source has been mitigated with signal enhancement. As a result, HSDPA users can receive macro-diversity gain through this soft handover support.

Similarly, in an OFDMA system, since the variables of matrix A are composed of frequency, time, and space, joint virtual scheduler 108 may perform all base stations of cluster 110a in given time slots to minimize overall interference. It may be possible to aggregate global sub-channel assignments in solidarity with the users of the domains 105. In an OFDMA system, interference management mitigates co-channel interference with signal enhancement. Moreover, the joint virtual scheduler 108 may achieve the purpose of universal reuse by tightly adjusting sub-channel allocation and transmission for neighboring cells such as cell 110 (2) and cell 110 (m). Can be.

To provide joint sub-channel assignments with a given maximum gain, the joint virtual scheduler 108 may assign a channel to users of maximum combined gain and minimum co-channel interference. This simplified matrix A represents the correlation of sub-channel sets for each base station 105 associated with each user, while sub-channel allocation and co-channel interference results in spatial attenuation from each base station to all users. can be characterized by spatial attenuation. The joint virtual scheduler 108 may divide all sub-channels for all cells 110 in the cluster 110a and may indicate a scheduling strategy for sub-channel allocation to each user. In this manner, the joint virtual scheduler 108 can coordinate transmission scheduling in an OFDMA system with maximum system performance.

In order to provide a scheduling strategy for coordinated regime scheduling in an OFDMA system, the joint virtual scheduler 109 is configured for all UEs from all base stations 105 in the cluster 110a, i.e. ATs 120, 125 in this cluster. The power for transmissions to the network may be scheduled, for example, in time and frequency domains. Power is allocated in such a way as to maximize the total throughput according to the power constraint for each base station 105. Joint virtual scheduler 108 may use Shannon capacity indicative of throughput, which implicitly indicates that data rates for ATs 120 and 125 may be selected.

In frequency domain scheduling at any given time, joint virtual scheduler 108 may maximize the total throughput / capacity. By adding scheduling in the time domain, the joint virtual scheduler 108 can solve the functional optimization problem. By first focusing on a given time, that is, frequency domain scheduling, the joint virtual scheduler 108 may provide parametric optimization, as defined below.

g _{i, j, k} = link gain (in power) from base station (BS) (i) to User Equipment (UE) or AT (k) on channel j. The link gain represents the correlation function for each user for each channel of all base stations in matrix A.

P _{i, j, k} = transmit power from BS (i) to UE (k) on channel j

here,

i ∈ {1, ..., I}, where I is the total number of base stations 105 in cluster 110a,

j ∈ {1, ..., J}, J is the number of subchannels in each base station 105 that can be allocated to the UEs,

k ∈ {1, ..., K}, K is the total number of UEs in the cluster 110a,

The following formula represents a problem formulation:

(1)

(One)

Below is subject to the maximum power limitation of each base station 105,

(2)

(2)

here,

(3)

(3)

Equation (3) is per UE capacity.

(4)

(4)

Equation (4) is the signal power for UE k on channel j.

(5)

(5)

Equation (5) is the common channel interference caused by UE k on channel j for all other users on that channel j,

(6)

(6)

Equation (6) is the inter-channel interference caused by the UE k on channel j for all other users who are channels other than j,

C _total is the total capacity of the cluster 110a and C _k is the capacity for the k-th UE.

W is bandwidth, which is assumed to be known.

Po is the maximum transmit power from base station 105 that is assumed to be the same and known for all base stations.

F _{^i, j,} is a channel (j) and channel ^(j,) attenuation (inter-channel attenuation) between the channels between. It is used to model interchannel interference and is assumed to be known. If only a given base transceiver station (BTS) transmits to one UE on a given channel, i.e., with a set of {P _{i, j, k} }, k = 1, ..., K, then {i, j} There is at most one non-zero element for any given pair.

The above formulated parameter optimization problem can be solved by traditional methods such as Lagrange multiplier method. However, the central controller, which is a large scale system with large dimensions, can optimize the total throughput by selecting IxJxK variables. In addition, in this case, the transmit power at each base station 105 may depend on many local constraints. To address the problem of central optimization and local constraints, the joint virtual scheduler 108 may use hierarchical control, and may use an iteration method to handle large dimensions by the central controller.

In accordance with one embodiment of the present invention, FIG. 4 shows the base station 105 (1, 2) from the cluster 110a of cells in order to maximize the total throughput or capacity for each base station 105 shown in FIG. Implement a method of scheduling power in the frequency domain for transmissions 130 (1, 2), 135 (1), 135 (2) to active access terminals 120 (1, 2) and 125 (1) Is a diagram illustrating a stylized representation. To this end, the parameter optimization algorithm 140 may include a high layer (HL) algorithm portion and a low layer (LL) algorithm portion, as shown in FIG. 4. As shown, the HL algorithm portion receives a power penalty, λ _i , i = l, ..., N from the LL algorithm portion. The HL algorithm portion allocates power by a small amount Δp by Δp. For each {i, j, k} there are three associated quantities:

1. Throughput Gain A _{i, j, k} (P)-The gain of throughput for itself when Δp is assigned to {i, j, k} taking into account the current power allocation ((P)

2. Co-Channel and Inter-Channel Interference Penalties B _{i, j, k} (P)-If Δp is assigned to {i, j, k} taking into account the current power allocation (P), the penalty ( Loss)

3. Base station power penalty (λ _i ), power penalty from LL algorithm portion.

In the HL algorithm part, the power calculation is described below, in which values of A _{i, j, k} , B _{i, j, k} can be calculated using partial directives evaluated for a given power allocation. do. For example, as shown in the HL algorithm section below:

Start HL_algorithm

Step 1: using the known link gains {g _{i, j, k} } and previous power allocation {P _{i, j, k} } in iteration n;

Step 2: Calculate S _{j, k} , I ^c _{j, k} and I ^l _{j, k} for all j, k using equations (4), (5), (6).

Step 3: Calculate A _{i, j, k} and B _{i, j, k} for all _{i, j, k} . here,

(6)

(6)

Similarly, the HL_algorithm determines B _{i, j, k} for all possible {i, j, k}.

Step 4: Calculate the TX credit for all i, j, k:

(8)

(8)

Step 5: order L _{i, j, k} in order, and if L _{i, j, k} > 0, then P _{i, j, k} = P _{i, j, k} + Δ

Step 6: Repeat until L _{i, j, k} <0

Terminate HL_algorithm.

In step 7, for each base station 105, the LL algorithm portion updates the power penalty, λ _i , i = l, ..., N and provides the power penalty to the HL algorithm portion. Finally, in step 8, the LL algorithm portion determines the power allocations {P _{i, j, k} } for each base station. However, to schedule power in the time domain, parameter optimization algorithm 140 may perform additional steps, as described below.

In accordance with one exemplary embodiment of the present invention, FIG. 5 is active from base stations 105 (1, 2) in a cluster of cells 110 a to optimize the total throughput or capacity for each base station shown in FIG. 1. Implementing a method of scheduling power in the time domain for transmissions 130 (1, 2), 135 (1), 135 (2) to access terminals 120 (1, 2), 125 (1) A diagram illustrating a stylized representation. At block 500, the maximization problem shown in FIG. 4 can be changed by adding a credit / penalty μi, j, k for " fairness. &Quot; At block 505, fairness can be maintained.

Table 1 below shows a joint scheduling scheduler 108 and a conventional scheduling algorithm, such as the Proportional Fair (PF) scheduler, with some metrics including priority ordering, credit, and penalty. Compare against.

Current scheduler Joint scheduler Priority ordering Ordering within each BTS Ordering for a pool of BTSs and sub-channels Credit rating Self-throughput (C / I) Self-throughput
Penalty
Fair Penalty (in time) Fair Penalty (in time) Co-channel and inter-channel interference for others TX power impact on specific BTS total power

In one embodiment, the high speed radio access network 115 may wirelessly communicate mobile data at the speed and coverage required by individual users or businesses. According to one embodiment, high-speed wireless data network 120 may include one or more data networks, such as an Internet Protocol (IP) network including the Internet and a public telephone system (PSTN). The third generation (3G) mobile communication system, i.e. Universal Mobile Telecommunication System (UMTS), supports multimedia services in accordance with the 3rd Generation Partnership Project (3GPP) specification. UMTS employs wideband code division multiple access (WCDMA) technology and includes packet switched networks, eg, core network (CN), which is IP-based networks. Due to the merging of the Internet and mobile applications, UMTS users can access both telecommunications and Internet resources. To provide end-to-end services to users, the UMTS network can use the UMTS bearer service layered architecture specified by the 3GPP standard. The provision of end-to-end service is carried over several networks and implemented by the interaction of protocol layers.

Portions and corresponding detailed description of the invention are provided by software or by representations of symbols and algorithms of operations on data bits in computer memory. These descriptions and representations are those by which those skilled in the art can effectively convey the substance of their work to others skilled in the art. As used herein, and as the term generally used, an algorithm is considered to be a self-consistent sequence of steps that yields a desired result. The steps are those requiring physical treatments of physical quantities. In general, but not necessarily, these quantities take the form of optical, electrical, or magnetic signals that can be stored, transmitted, combined, compared, or otherwise manipulated. At times, it has proved convenient to refer to these signals as bits, values, elements, symbols, characters, terms, numbers, etc., mainly for general use reasons.

However, it should be noted that all these and similar terms are associated with appropriate physical quantities and are merely convenient labels applied to these quantities. Unless specifically stated otherwise, or as apparent from the discussion, such as "processing" or "computing" or "calculating" or "determining" or "displaying", etc. The terms process data expressed in physical and electrical quantities in registers and memories of a computer system into other data similarly represented as physical quantities in computer system memories or registers or other such information storage, transfer or display devices. Represents the operations and processes of a transforming computer system, or similar electronic computing device.

It is also noted that software implemented aspects of the present invention are typically encoded on some form of program storage medium or implemented on some type of transmission medium. The program storage medium may be magnetic (eg, floppy disk or hard disk) or optical (eg, compact disc read only memory, or “CD-ROM”), and may be read only or random access. Similarly, the transmission medium may be twisted wire pairs, coaxial cable, optical fiber, or some other suitable transmission medium known in the art. The invention is not limited by these aspects of any given implementation.

The invention will now be described with reference to the accompanying drawings. Various structures, systems and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present invention with details known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present invention. The words and phrases used herein are to be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by the person concerned. There is no specific definition of a word or phrase, that is, definitions that differ from the general and customary meanings as understood by one of ordinary skill in the art are intended to be encompassed by the use of consistent words or phrases herein. In order to extend a word or phrase to a particular meaning, that is, intended to have meanings other than those understood by those skilled in the art, such particular definitions are defined in the specification in a clear manner that directly and explicitly provides a particular definition for the word or phrase. Will be specifically explained.

Although the present invention has been illustrated herein as being useful in a telecommunications network environment, it also applies to other connection environments. For example, the two or more devices described above may be hard cabling, radio frequency signals (e.g., 802.11 (a), 802.11 (b), 802.11 (g), 802.16, Bluetooth, etc.), It may be coupled together via device-to-device connections, such as infrared coupling, telephone lines and modems, and the like. The present invention can be applied to any environment in which two or more users can be interconnected and communicate with another user.

Those skilled in the art will appreciate that the various system layers, routines, or modules described in the various embodiments herein are executable control units. The controllers may include a microprocessor, microcontroller, digital signal processor, processor card (including one or more microprocessors or controllers), or other control or computing devices. Storage devices can include one or more machine-readable storage media for storing data and instructions. Storage media include dynamic or static random access memories (DRAMs or SRAMs), erasable and programmable read-only memories (EPROMs), electrically erasable and programmable read-only memories (EEPROMs) and Semiconductor memory devices such as flash memories; Magnetic disks such as fixed, floppy, removable disks; Other magnetic media including tape; And different forms of memory, including optical media such as compact discs (CDs) or digital video discs (DVDs). Instructions that form the various software layers, routines, or modules of the various systems may be stored in respective storage devices. The instructions, when executed by the controllers, cause the corresponding system to perform programmed operations.

The specific embodiments described above are illustrative only, and the invention may be modified and practiced in different but equivalent ways apparent to those skilled in the art having the benefit of the teachings herein. Moreover, there is no intention to limit the details of the construction or design shown herein, other than as described in the claims below. Accordingly, it is apparent that the specific embodiments described above may be changed or modified, and all such changes are considered within the scope and spirit of the present invention. Accordingly, the protections obtained herein are as recorded in the following claims.

Claims (16)

delete delete delete delete delete delete delete delete delete A method for scheduling transmission by a plurality of base stations providing services to a plurality of users in a wireless communication system, the method comprising: Calculating, at the scheduling apparatus, a throughput gain for the plurality of subchannels between each user and each base station resulting from increasing the power allocated to each subchannel by the selected amount; Calculating, at the scheduling apparatus, interference penalty for a plurality of subchannels between each user and each base station resulting from increasing the power allocated to each subchannel by the selected amount, wherein The interference penalty calculation step indicating a loss of throughput of other users resulting from increasing power by the selected amount; In the scheduling apparatus, a transmission credit for each subchannel is set by setting each transmission credit equal to a throughput gain for each subchannel and an amount of difference between an interference penalty and a power penalty for each subchannel. Calculating a credit), wherein the power penalty indicates a difference between the maximum power and the allocated power for each base station; And And in the scheduling apparatus, assigning increased power to each subchannel based on the transmission creditworthiness. 11. The method of claim 10, The calculating of the throughput gain is based on the power allocated to each of the plurality of subchannels and the link gain for each of the plurality of subchannels before increasing the power allocated to each subchannel by the selected amount. Calculating the throughput gain. 11. The method of claim 10, And calculating the interference penalty includes calculating at least one of a co-channel interference penalty or an inter-channel interference penalty. 13. The method of claim 12, The calculating of the interference penalty is based on the power allocated to each of the plurality of subchannels and the link gain for each of the plurality of subchannels before increasing the power allocated to each subchannel by the selected amount. Calculating the interference penalty. 11. The method of claim 10, Allocating the increased power, Increasing the power allocated to the subchannels when the maximum value of the transmit credit of the subchannels exceeds a threshold; Recalculating the throughput gain, the interference penalty, and the transmit credit using the additional increased value of the power allocated to the subchannels; And Determining the final increased value of the allocated power by repeating the incrementing and recalculating until the maximum value of the transmit credit for all subchannels is below the threshold. . The method of claim 14, And allocating the increased power comprises recalculating a power penalty for each of the base stations based on the last increased value of the allocated power. The method of claim 15, Determining whether the recalculated value of the power penalty for each of the base stations differs from a previous value of the power penalty for each of the base stations to an extent less than a threshold; And Repeating the calculation of the throughput gain, interference penalty, and transmit credit using the recalculated value of the power penalty for each of the base stations until the difference is less than the threshold.

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